Energy transfer device



June 3, 1969 HSIN SHENG CHEN 3,447,398

- ENERGY TRANSFER DEVICE Filed July 27. 19s? 9 J Z UPPER MASS s 5 SPEED 2 g g 6 LOWER MASS FIG. 3 V I INVENTOR HS/N SHE/v6 CHE/v F/G'. 2v gw/flzam ATTORNEY United States Patent US. Cl. 74-752 3 Claims ABSTRACT OF THE DISCLOSURE Apparatus for converting the low torque rotation of a prime mover into a high torque and increased amplitude oscillating output without increasing the torque reaction to the operator. The high torque output may be used for any application. The apparatus includes a motor which drives a pair of eccentric weights which are mounted on an upper mass. Centrifugal force developed by the rotation of the eccentric weights produces an oscillating torque acting on the upper mass. There is a torsion bar which connects the upper mass to a lower mass. The torsion bar transfers the torque produced at the upper mass to the lower mass to oscillate the lower mass at a large amplitude. A one-way clutch may be provided at the lower mass to provide a unidirectional output.

Background of the invention This invention relates to a torsionally oscillating energy transfer device and more particularly to apparatus which employs the storage and release of oscillating energy. It has been known in the past to use vibratory energy to produce a rotational or reciprocating output. Some prior art devices use a rotary motor to rotate a pair of eccentric weights to produce vibration for use in a power tool. The disadvantage of prior art devices is that the operator must absorb the same amount of vibrations as are transferred to the workpiece. Prior apparatus which has reduced or eliminated the vibration to the operator are capable of eliminating the transfer of vibrations to the operator at one operating speed only.

Summary It is therefore the principal object of this invention to provide an energy transfer device which amplifies torque and eliminates the transfer of tool vibrations to the operator regardless of the speed at which the tool is operated.

It is another object of this invention to provide an energy transfer device which employs vibratory energy and is capable of producing a unidirectional output.

In general, these objects are carried out by providing apparatus for producing a rotational output which includes a casing, an upper mass mounted for rotary movement relative to the casing and means for producing rotary oscillating energy in said upper mass. There is a lower mass mounted for rotational movement with respect to the casing and provided with means adapted to have a workpiece connected thereto. Means are mounted within the casing connecting the lower mass to the upper mass and adapted to rotate with the upper mass for storing the rotary oscillating energy of the upper mass and releasing the stored energy to the lower mass to thereby rotate the lower mass.

Brief description of the drawing The foregoing and other objects will become apparent from the following description and drawings wherein:

FIG. 1 is a sectional view showing a wrench employing one embodiment of the present invention;

FIG. 2 is a sectional view taken on the line 2--2 of FIG. 1 looking in the direction of the arrows; and

FIG. 3 is a graph showing the theory of operation of this invention.

Description of the preferred embodiment Referring to FIGS. 1 and 2, there is shown one embodiment of this invention as applied to a wrench and includes a casing generally indicated at 30. An upper mass 10 is rotatably mounted within the casing 30 by means of a bearing 13. A pair of eccentric weights 8 and 9 are mounted on shafts 6 and 7, respectively, 180 out of phase from each other. The shafts 6 and 7 and thus the Weights 8 and 9 are rotatably mounted on the upper mass 10 by means of sleeves 11 and 12. A pair of spur gears 4 and -5 are mounted on the other end of shafts 6 and 7, respectively. Any suitable rotary motor 1 is connected to the casing 30 and includes a drive shaft 2. A main spur gear 3 is mounted on the drive shaft 2 and engages spur gears 4 and '5.

As the main gear 3 rotates, the gears 4 and 5 and thus the eccentric weights 8 and 9 are rotated. As the eccentric weights are rotated, centrifugal force' is developed by each weight in an amount equal to and in a direction opposite the other weight. The centrifugal force developed by the two rotating eccentric weights is transferred to the upper mass 10 and will tend to rotate the upper mass. In the position shown in FIG. 2, the direction of the centrifugal force of the eccentric weights is parallel to the longitudinal axis of the upper mass, the two forces will cancel each other out and there will be no rotation of the upper mass. When the weights have rotated counterclockwise, which may be referred to as position one, the direction of the centrifugal force of the two weights will be complementary to each other and tend to cause the upper mass to rotate. As the weights rotate an additional 90, the centrifugal force of the two weights will again cancel each other out. With an additional rotation of 90, which may be referred to as position two, the centrifugal force will again be complementary but at this time in a direction opposite to the first direction and the upper mass will tend to rotate but in a direction opposite to that when the weights 8 and 9 were in position one. Thus the upper mass tends to oscillate within the housing 30. It is believed that the oscillation of the upper mass 10 is in a direction opposite to the direction of the torque produced by the eccentric weights and the amplitude of these oscillations has been indicated as negative in FIG. 3.

A torsion bar generally indicated at 15 is connected to the upper mass by means of a bolt 14. The torsion bar 15 is sufficiently long to allow a certain amount of flexing and twisting motion. The exact length of the torsion bar will depend upon the application of the tool.

A lower mass 16 is connected to the opposite ends of the torsion bar 15 and rotatably mounted in the housing 30 by means of bearings 17 and 18. A one-way clutch 20 is connected to the lower mass 16 by suitable keying means. The one-way clutch has an output means 25 which is adapted to rotate in bearings 26.

As was hereinbefore stated, as the motor drives the eccentric weights 8 and 9, centrifugal force will produce rotary oscillating torque in the upper mass 10. This rotary oscillating energy will be stored by the torsion bar 15 and released to the lower mass 16 and thus to the one-way clutch 20. Since the one-way clutch is employed, there will be a unidirectional output at the output means 25. As can be seen from FIG. 3, at lower speeds the oscillation of both the upper and lower mass is in the same direction and has been indicated as negative when compared to the direction of the centrifugal torque produced by the weights 8 and 9. As speed increases, the amplitude of the oscillations of the upper mass decrease and the amplitude of the lower mass oscillations begin to increase. The torsion bar with its energy storing and releasing function must be credited with the increased amplitude of the oscillations of the lower mass.

At a certain speed, point A on FIG. 3, which is the. optimum operating frequency of the tool, the upper mass will remain substantially stationary but the centrifugal force will be transferred through the torsion bar which stores and releases energy to oscillate the lower mass at a relatively large amplitude. IIn one such tool the motor speed was approximately 7500 rpm. and the lower mass oscillated 8 while the upper mass remains substantially stationary. As speed is further increased, the upper mass begins to oscillate again and it is believed it is in a direction which is the same as the direction of the torque produced by the eccentric weights. As speed is increased further the amplitude of the oscillation of the upper mass will begin to approach infinity. The amplitude of theoscillation of the lower mass will greatly increase in a direction opposite to that of the upper mass.

However, in actual practice the lower mass achieves a certain amplitude and then begins'to oscillate in the same direction as the direction of the centrifugal force applied to the upper mass.

With the torsion bar storing and releasing the rotary oscillating energy of the upper mass, the amplitude of the oscillations of the lower mass is amplified. With the increased amplitude, it is possible to use a one-way clutch to achieve a unidirectional output. Since most one-way clutches permit approximately a 3 slippage, a practical tool requires an oscillation of at greater than 3 to achieve a unidirectional output. Anything less than a 3 amplitude would not permit the tool to be used as a wrench. When the motor is driving the vibratory system at the optimum speed, point A on FIG. 3, the upper mass does not vibrate. At other speeds, the upper mass 'vibrates but no vibration is transferred to the operator because the operator does not hold any vibrating parts. The tool is held by the casing 30 which does not vibrate. All vibrating parts move relative to the casing. Thus, unlike a shock absorber which would permit vibration of a body at a particular frequency without transfer of vibrations to the operator, this invention permits operation at all frequencies without vibration to the operator. The tool is capable of operating within a speed range.

The torque output of a tool made in accordance with the principles of this invention is controlled by motor speed and the size of the eccentric weights 8 and 9, not the torque of the motor. In one tool tested where the optimum speed was determined to be 7500 r.p.m., a torque of 50 foot pounds was achieved. If the motor speed is increased, the torque will increase. If the weight of the eccentrics 9 and 10 were increased, the torque output will increase since centrifugal force depends on weight eccentricity and rotational speed. Each tool made in accordance with this invention will have a certain speed range and thus a certain torque range. Another tool having different weight eccentrics will have a different torque range.

Although I have shown as a working embodiment the use of this invention as a wrench used for tightening fasteners, it is intended that this invention may be applied to other fields such as rock drilling. "In rook drilling, the unidirectional output would not be necessary. The apparatus could be used in place of the rotary motor of a drilling system. The bit which would be \connected to the output system would require a number of cutting surfaces equal to the amplitude of the oscillations divided into a 360 circle. In other words, if a star-type bit were employed and the system were capable of achieving a 10 amplitude at the output then 36 cutting surfaces would be used on the drill bit. This would allow complete cutting at the bottom of the hole.

Although I have described but one preferred embodiment it is intended that the foregoing description not be limiting in any way. It is intended that the invention be only limited by that which is Within the scope of the appended claims.

I claim:

1. Apparatus for producing a rotational output comprising:

a casing;

a first mass mounted in one end of said casing for rotary movement relative to said casing;

eccentric weight means rotatably mounted on said first mass;

means for rotating said eccentric weight means relative to said casing and said first mass for producing rotary oscillating energy in said first mass;

21 second mass mounted at the other end of said casing for rotational movement relative to said casing and having means adapted to have a workpiece connected thereto; and

torsion bar means disposed in said :casing and secured to said first mass and said second mass for storing the rotary oscillating energy produced in said first mass by said eccentric Weight means and releasing the stored energy to said second mass to thereby rotate said second mass.

2. The apparatus of claim 1 wherein said second mass includes a one way clutch for producing a unidirectional output.

3. The apparatus of claim 2 wherein said first and second masses are mounted on bearings.

References Cited UNITED STATES PATENTS 3,263,529 8/1966 Borisotf 74-751 1,864,824 6/1932 Hobbs 74752 2,077,556 4/ 1937 Gaston 74--752 3,151,493 10/1964 Geyer 74--752 X ARTHUR T. MCKEON, Primary Examiner.

US. Cl. X.R. 74773 

